JPH0682108B2 - Steam dryness meter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a steam dryness meter used for heat management of various boilers, equipment utilizing steam power, drying equipment, etc.
In particular, the present invention relates to a vapor dryness meter capable of measuring the dryness of vapor at low pressure or low dryness.

2. Description of the Related Art Conventionally, for example, as an apparatus for measuring the dryness of a predetermined wet steam, there is a throttle dryness meter that utilizes isenthalpic change of steam. This is because moist steam is injected through an orifice into a measuring vessel equipped with a thermometer and a pressure gauge for adiabatic expansion to bring it into a superheated state, and each temperature value, pressure value, and Moliere diagram or saturated steam table, superheated steam table. Is used to measure the dryness.

Problems to be Solved by the Present Invention In the above case, there is a problem that the measurable pressure range and the dryness range of the wet steam are limited and only a part of the wet steam can be measured. That is, when the pressure of the wet steam to be measured is low, it is necessary to lower the pressure inside the measurement container in order to bring it into the superheated steam state, but the conventional device cannot lower the pressure below atmospheric pressure, and When the dryness is low, it cannot be measured because the state of superheated steam does not occur after adiabatic expansion.

For the above problem, as the other vapor dryness measuring device, the wet steam to be measured is caused to flow in the inner pipe of the double pipe, and the same amount of superheated steam is caused to flow to the outer pipe to heat the wet steam to be measured by this superheated steam. It is known to vaporize by superheat and measure the dryness. However, flowing the same amount of superheated steam as the steam to be measured and sampling the steam to be measured in this device could not be a practical device due to the problems that the device becomes large and complicated.

Further, in the conventional apparatus, when the steam pressure to be measured fluctuates, the pressure inside the measuring container also fluctuates, and the dryness is recalculated by reading the pressure value each time, which is complicated.

Therefore, the technical problem of the present invention is to make it possible to easily measure the dryness of low-pressure wet steam or steam of low dryness.

Means for Solving the Problems The technical means of the present invention taken to solve the above technical problems are provided with an introduction passage for introducing the steam to be measured into the measurement part, and the introduction passage has a valve and a heat receiving means or We arrange heat dissipation means,
A pressure reducing valve that is provided with a temperature detecting means in the measuring section and communicates with the bleeding means in the measuring section, and opens the valve when the measuring section becomes lower than the set pressure and closes it when the measuring pressure becomes equal to the set pressure. It was done.

Action The action of the above technical means is as follows.

By depressurizing the inside of the measurement container with the bleeding means via the pressure reducing valve, the pressure drop of the steam to be measured becomes larger than that of the conventional throttling using only the orifice, and the pressure inside the measurement container can be kept constant. If the pressure drop becomes large, even if the pressure of the steam to be measured itself is low, it can be converted into superheated steam and the dryness can be measured. Also, in a vapor dryness meter that uses isenthalpic change, the greater the pressure drop, the greater the dryness of the wet vapor, and the vapor to be measured that has a low dryness can be superheated to measure the dryness. can do.

Further, even in the case of wet steam that cannot be superheated into steam even if the pressure is reduced by the pressure reducing valve and the bleeding means,
Saturated vaporization can be achieved by supplying heat quantity by the heat receiving means, and the dryness can be measured. Also,
By consuming the amount of heat by the heat radiating means, the liquid can be saturated and liquefied, and the dryness can be measured. That is, in the vapor diagram (T / S diagram) shown in FIG. 2, K
With the critical point as the critical point, the dryness of wet steam at temperature T1: M
The point can be expressed by the ratio between the saturated liquid point B1 (dryness = 0) on the saturated liquid line and the saturated vapor point C1 (dryness = 1) on the saturated vapor line, and the heat supply amount by the heat receiving means, that is, M The above ratio can be calculated by knowing the amount of heat between -C1 or by knowing the amount of heat consumed by the heat radiating means, that is, the amount of heat between M-B1, and the dryness can be measured.

EFFECTS OF THE INVENTION The present invention produces the following unique effects.

It can generate a larger pressure drop than a throttle with only an orifice, and does not need to flow the same amount of superheated steam as the steam to be measured, and measures the dryness of low-pressure wet steam or low-dry steam with a simple structure. can do.

Further, by keeping the pressure in the measurement container constant via the pressure reducing valve, it is not necessary to read the pressure value and recalculate the dryness even if the steam pressure to be measured fluctuates, so that the measurement can be easily performed. .

In addition, even for low-pressure wet steam that cannot be superheated by the pressure reducing valve and the bleeding means and vapor with low dryness, the dryness can be measured by saturating or liquefying saturated vapor. It can measure the dryness of wet steam under any condition.

Example An example showing a specific example of the above technical means will be described.
(Refer to FIG. 1 and FIG. 2) FIG. 1 is a diagram showing the structure of a steam dryness meter, in which 1 is a steam main pipe for measuring the dryness of steam in the main pipe 1. A measuring portion 5 is connected to an introduction passage 2 branched from the main pipe 1 via a pressure reducing valve 3 and a heat receiving or radiating means 4. A heater such as an electric heater is used as the heat receiving means, and a radiator or the like is used as the heat radiating means. Further, the amount of work may be converted into the amount of heat using a pump, a turbine, or the like. The heat receiving or heat radiating means 4 is provided with a display portion 4a for calculating and displaying the amount of heat. A temperature sensor 6 as a temperature detecting means is mounted in the measuring section 5. A vacuum pump 7 as a bleeding unit is arranged in communication with the measuring unit 5. The pressure reducing valve 3 is opened to supply steam when the inside of the measuring unit 5 is pulled by the vacuum pump 7 and becomes lower than the set pressure of the pressure reducing valve 3, and is closed when the pressure becomes equal to the set pressure. The temperature sensor 6 detects the temperature in the measuring unit 5. A pressure gauge 8 for detecting the pressure of steam to be measured is attached to the steam main pipe 1. However, the pressure gauge 8 is not necessary when the pressure of the steam to be measured is known.

In order to measure the dryness X in the dryness meter, the pressure P1 of the steam to be measured in the steam main pipe 1 is measured by the pressure gauge 8 and the temperature T2 of the superheated steam after adiabatic expansion through the pressure reducing valve 3 is carried out by a temperature sensor. The measured vapor pressure P1 can be calculated from the read value and the saturated steam table and the superheated steam table.
, Saturated water enthalpy I1 ″ of measured steam pressure P1, saturated temperature enthalpy I1 ″ of measured steam pressure P5, temperature T2 in the measuring unit 5 and enthalpy I2 of superheated steam at the set pressure P2 of the pressure reducing valve 3, It can be calculated from the formula.

In the case of wet steam that cannot be superheated into steam even if the pressure is reduced by the pressure reducing valve 3 and the vacuum pump 7, that is, in the steam diagram of FIG. Even when it becomes wet steam at the point M without becoming superheated steam after adiabatic expansion, for example, the heat quantity Q corresponding to M-C1 by the heat receiving means 4 is supplied by the temperature sensor 6 until the temperature T1 begins to rise. When,
By measuring from the relationship between the measured steam pressure P1 and the measured steam amount obtained by the differential pressure between the set pressure of the pressure reducing valve 3, the dryness X ′ is It can be calculated from the formula. Where Ic1 is the saturated vapor point C1
Is the enthalpy in. Similarly, the dryness X ″ can also be obtained by measuring the amount of heat Q ′ corresponding to M−B1 by the heat radiating means 4.

By supplying or consuming the amount of heat by the heat receiving or radiating means 4, it is possible to easily measure the dryness of any low-pressure wet steam or steam of low dryness.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a steam dryness meter according to one embodiment of the present invention, and FIG. 2 is a steam diagram showing changes in the state of steam. 1: Steam main pipe, 2: Inlet passage 3: Pressure reducing valve, 4: Heat receiving or heat radiating means 5: Measuring part, 6: Temperature sensor 7: Vacuum pump, 8: Pressure gauge

Claims (1)

[Claims] 1. An introduction passage for introducing the steam to be measured into the measuring section is provided, a valve and a heat receiving means or a heat radiating means are arranged in the introducing passage, temperature measuring means is provided in the measuring section, and bleeding means is provided in the measuring section. A vapor dryness meter characterized in that, when connected to each other, the above valve is a pressure reducing valve that opens when the measuring unit becomes lower than a set pressure and closes when the measuring unit becomes equal to the set pressure.